From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH] Revert "cpufreq: pcc-cpufreq: update default value of cpuinfo_transition_latency" Date: Fri, 22 Jul 2016 16:30:42 -0700 Message-ID: <20160722233042.GI3122@ubuntu> References: <20160722151411.GB11711@suselix.suse.de> <3431802.ZZWypmTthK@vostro.rjw.lan> <20160722212852.GE3122@ubuntu> <3860863.MLaNBM27lJ@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <3860863.MLaNBM27lJ@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Andreas Herrmann , Jacob Tanenbaum , stable@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-pm@vger.kernel.org On 22-07-16, 23:46, Rafael J. Wysocki wrote: > On Friday, July 22, 2016 02:28:52 PM Viresh Kumar wrote: > > On 22-07-16, 23:31, Rafael J. Wysocki wrote: > > > > cpufreq.c > > > > > > > > if (policy->governor->max_transition_latency && > > > > policy->cpuinfo.transition_latency > > > > > policy->governor->max_transition_latency) { > > > > > > > > - And this check will always fail, unless max_transition_latency is zero. > > > > > > Why would it fail? If governor->max_transition_latency is non-zero, but less > > > than UNIT_MAX, the condition checked will be true to my eyes. > > > > Bad wording. Sorry. > > > > I meant, this 'if' check will always succeed (as you also noted), and > > so we will always get the error message reported in this patch. > > Not always, but for drivers setting cpuinfo.transition_latency to CPUFREQ_ETERNAL. So the drivers which have set their transition_latency to CPUFREQ_ETERNAL, can't use ondemand governor unless governor->max_transition_latency is set to 0 from userspace. What should be done about this patch then ? It broke in late 2015. -- viresh